package net.mindView.concurrency;

import java.util.ArrayList;
import java.util.List;
import java.util.Random;
import java.util.concurrent.*;

public class HorseRace {
    static final int FINISH_LINE = 75;
    private List<Horse> horses = new ArrayList<Horse>();
    private ExecutorService exec = Executors.newCachedThreadPool();
    private CyclicBarrier barrier;
    public HorseRace(int nHorses,final int pause){
        barrier = new CyclicBarrier(nHorses, new Runnable() {
            @Override
            //当所有Horse都调用await()后，执行该方法
            public void run() {
                StringBuilder s = new StringBuilder();
                for(int i=0;i<FINISH_LINE;i++)
                    s.append("=");
                System.out.println(s);
                for(Horse horse:horses){
                    System.out.println(horse.tracks());
                }
                for(Horse horse:horses){
                    if(horse.getStrides() >= FINISH_LINE){
                        System.out.println(horse + " won!");
                        exec.shutdownNow();
                        return;
                    }
                }
                try {
                    TimeUnit.MILLISECONDS.sleep(pause);
                }catch (InterruptedException e){
                    System.out.println("barrier-action sleep interrupted");
                }
            }
        });
        for(int i=0;i< nHorses;i++){
            Horse horse = new Horse(barrier);
            horses.add(horse);
            exec.execute(horse);
        }
    }

    public static void main(String[] args) {
        int nHorse = 6;
        int pause = 200;
        new HorseRace(nHorse,pause);
    }
}

class Horse implements Runnable{
    private static int counter = 0;
    private final int id = counter++;
    private int strides = 0;
    private static Random rand = new Random(47);
    private static CyclicBarrier barrier;
    public Horse(CyclicBarrier b){ barrier = b; }
    public synchronized int getStrides(){ return strides; }
    public void run(){
        try{
            while(!Thread.interrupted()){
                synchronized (this){
                    strides += rand.nextInt(3);
                }
                barrier.await();
            }
        }catch (InterruptedException e){

        }catch (BrokenBarrierException e){
            throw new RuntimeException();
        }
    }
    public String toString(){ return "Horse " + id + " "; }
    public String tracks(){
        StringBuilder s = new StringBuilder();
        for(int i=0;i < getStrides(); i++){
            s.append("*");
        }
        s.append(id);
        return s.toString();
    }
}

